SpringData用於聚合的mongoDB API $ map

Question

以下是我的Native MongoDB查詢，下面是SpringData Mongo API等效項。在SpringData Mongo API中，我正在使用$ project中的$ map。欣賞在完成我的轉換API

db.users.aggregate([  
    { $match: {$and : [{userType:"200"} },  
    { $unwind: "$userOrgMap" }, 
    { 
     $lookup: 
     { 
      from: "users", 
      localField: "userOrgMap.createdbyuser", 
      foreignField: "_id", 
      as: "created_by" 
     } 
    }, 
    {$project:{ 
     _id:"$_id", 
     login:"$login", 
     firstName:"$firstName", 
     lastName:"$lastName", 
     email:"$email", 
     deactivateFlag:"$deactivateFlag", 
     createdOn:"$createdOn", 
     createdBy:{ 
     "$map": { 
        "input": "$created_by", 
        "as": "u", 
         "in": { 
          "name": { "$concat" : [ "$$u.firstName", " ", "$$u.lastName" ] }, 
         } 
       } 
    } 
     } 
    }, 
    { $sort : { createdBy : 1} } 

]) 

春查詢

Aggregation aggregation = newAggregation(
      Aggregation.match(Criteria.where("userType").is(userType)), 
      Aggregation.unwind("userOrgMap"), 
      Aggregation.lookup("users", "userOrgMap.createdbyuser", "_id", "created_by"), 
      Aggregation.project("userId","login","firstName","lastName","email","deactivateFlag","createdOn") 
     ); 

Answer 1

你可以試試下面$map聚集你的幫助。

project().and(mapItemsOf("created_by"). 
          as("u"). 
          andApply(new AggregationExpression() { 
           @Override 
           public DBObject toDbObject(AggregationOperationContext aggregationOperationContext) { 
            return new BasicDBObject("name", StringOperators.valueOf("u.firstName").concat(" ").concatValueOf("u.lastName").toDbObject(aggregationOperationContext)); 
           } 
          })) 
      .as("createdBy"); 

使用$let表達

project().and(VariableOperators.Let.define(VariableOperators.Let.ExpressionVariable.newVariable("u").forExpression(ArrayOperators.arrayOf("created_by").elementAt(0))). 
          andApply(new AggregationExpression() { 
           @Override 
           public DBObject toDbObject(AggregationOperationContext aggregationOperationContext) { 
            return new BasicDBObject("name", StringOperators.valueOf("u.firstName").concat(" ").concatValueOf("u.lastName").toDbObject(aggregationOperationContext)); 
           } 
          })) 
      .as("createdBy"); 

使用Lambda和靜態導入。

import static org.springframework.data.mongodb.core.aggregation.ArrayOperators.arrayOf; 
import static org.springframework.data.mongodb.core.aggregation.StringOperators.valueOf; 
import static org.springframework.data.mongodb.core.aggregation.VariableOperators.Let.ExpressionVariable.*; 
import static org.springframework.data.mongodb.core.aggregation.VariableOperators.Let.define; 
import static org.springframework.data.mongodb.core.aggregation.VariableOperators.mapItemsOf; 

project().and(mapItemsOf("created_by"). 
       as("u"). 
       andApply(aggregationOperationContext -> new BasicDBObject("name", valueOf("u.firstName").concat(" ").concatValueOf("u.lastName").toDbObject(aggregationOperationContext)))) 
       .as("createdBy"); 

    project().and(define(newVariable("u").forExpression(arrayOf("created_by").elementAt(0))). 
      andApply(aggregationOperationContext -> new BasicDBObject("name", valueOf("u.firstName").concat(" ").concatValueOf("u.lastName").toDbObject(aggregationOperationContext)))) 
      .as("createdBy");